1. Field of Invention
The invention relates to a control system for an electromagnetically driven valve provided in an internal combustion engine.
2. Description of Related Art
JP-A-11-62529 discloses the technology for adjusting control frequency of a switching element upon control of exciting current supplied to an electromagnetic coil. In the aforementioned publication, the control frequency of the switching element is set to a high frequency upon displacement of a movable member of the electromagnetically driven valve so as to reduce operation noise generated when the movable member reaches one of displacement ends. Meanwhile the control frequency of the switching element is set to a low frequency when the movable member is held in the displacement end so as to suppress an energy consumption and heat generation owing to switching loss as least as possible.
The displacement of the movable member does not always require setting of the control frequency of the switching element to the high value. In the aforementioned publication, however, as the control frequency of the switching element is always set to the high value upon displacement of the movable member, the energy consumption and heat generation owing to switching loss unnecessarily occur.